The Journal Of Animal Ecology[JOURNAL]
Sun
200 papers
Beyond first clutches: Second broods reshape selection on breeding timing in forest and urban great tits.
Defrance J, Lambrechts M, Fargevieille A … +3 more , Perret S, Grégoire A, Charmantier A
J Anim Ecol · 2026 Jul · PMID 42198834 · Full text
Urbanisation provides a unique framework for studying how organisms respond to human-modified environments. Although phenotypic differences between rural and urban populations are increasingly well documented, our knowle...
Urbanisation provides a unique framework for studying how organisms respond to human-modified environments. Although phenotypic differences between rural and urban populations are increasingly well documented, our knowledge of how natural selection operates in cities remains limited. In particular, few studies have quantified the direction and shape of natural selection acting on breeding phenology in urban environments. Using a 13-year dataset on great tits (Parus major), we investigated how first clutch laying date (FCLD) influences both fledgling output from first broods and total seasonal productivity (first and second clutches combined). We first tested whether FCLD differed between habitats and among urban plots. We then estimated natural selection on FCLD relating breeding phenology to fledgling number from (i) first broods only and (ii) total annual productivity including first and second broods. Finally, we evaluated how FCLD and habitat jointly affected the probability of multiple brooding. As in previous studies, FCLD occurred earlier in more urbanised areas. With first broods only, earlier breeding tended to be associated with higher fledging numbers in forest but not in urban habitats. In contrast, when including second clutches, a higher annual productivity was found for earlier breeders in both habitats. When controlling for clutch size, no direct selection on FCLD was detected. Earlier breeders were also more likely to initiate a second clutch, particularly in urban populations. Finally, structural equation models further showed that the effect of FCLD on annual fledgling production was largely indirect, mediated by the probability of multiple brooding and the resulting increase in annual egg number. Together, our analyses suggest that earlier laying females achieve higher annual fledgling productivity, mainly determined by a higher probability of double brooders and the resulting higher seasonal egg production in both forest and city. In general, these results highlight the importance of evaluating selection using annual reproductive output rather than single breeding attempts. We believe that the underlying proximate mechanism that may promote this advantage may be related to the dynamics of prey abundance throughout the birds' breeding season, and we encourage further studies that would compare these prey dynamics across habitats.
malddaba: An open-access database of age-specific mammalian demography for comparative analyses in evolutionary biology and demography.
Ronget V, Lemaître JF, Spataro B … +2 more , Humblot L, Gaillard JM
J Anim Ecol · 2026 May · PMID 42198827 · Publisher ↗
The question of how individual age influences demographic transition rates, such as survival probabilities and reproduction rates, has long been a main question for demographers and evolutionary ecologists. This has resu...
The question of how individual age influences demographic transition rates, such as survival probabilities and reproduction rates, has long been a main question for demographers and evolutionary ecologists. This has resulted in the accumulation of studies estimating the age-specific demographic transition rates across the tree of life over the last few decades. Although this accumulation of studies has enabled comparative demographic analyses to be developed, such analyses remain difficult to perform because age-specific data are scattered across literature. Here, we present a new open-access database, malddaba, which compiles age-specific demographic rates for mammals in the wild from published information. Currently, the database encompasses 174 species from 255 publications, representing 437 age- and sex-specific survival series and 201 age- and sex-specific reproduction series. Each series is reported using a standardized approach aimed at facilitating the extraction and use of that dataset by anyone interested in comparative evolutionary biology and demography. We show how malddaba can be used to address a variety of questions, ranging from comparative ageing with the assessment of actuarial and reproductive senescence patterns in a wide diversity of mammals to comparative population dynamics. For this purpose, in addition to the raw demographic rate records, we were able to build 45 population-specific life tables using malddaba records, which allow demographic outputs to be estimated accurately, such as population growth rate and generation time for those species. The malddaba database will be regularly updated to keep adding new demographic estimates and bring a comprehensive and dynamic view of the diversity of demographic trajectories across mammals.
Multiple routes to territory inheritance in Florida Scrub-Jays (Aphelocoma coerulescens).
Beres SK, Bakley TD, Summers J … +2 more , Fitzpatrick JW, Barve S
J Anim Ecol · 2026 Jul · PMID 42189840 · Full text
In many animals, being the dominant owner of a territory is a pre-requisite for reproductive success. Acquisition of territory by inheritance, where at least a portion of the new (breeding) territory is acquired from the...
In many animals, being the dominant owner of a territory is a pre-requisite for reproductive success. Acquisition of territory by inheritance, where at least a portion of the new (breeding) territory is acquired from the natal territory, characterizes many social animals and offers multiple benefits over dispersing away from natal ground. Territory dynamics change rapidly and are difficult to objectively quantify. Additionally, little is known regarding the non-dispersive sex's potential to inherit. We spatially analysed decades of territory maps to identify all nontrivial instances of natal territory inheritance in first-time breeding Florida Scrub-Jays (Aphelocoma coerulescens) and compared initial reproductive success of those that gained breeding status through any form of inheritance versus by other means. Among inheritors, we studied how first-time territory acquisition strategies differed between the sexes. Between 1982 and 2024, 139 out of 1014 first-time breeders gained significant natal territory through inheriting the entire natal territory upon the death of both parents, pairing with an adjacent, widowed neighbour and incorporating some natal ground, or pairing with a novice disperser and budding off of their natal territory (or some combination of two). Among all breeders that inherited substantial portions of natal territory, males did so about twice as often as females (97 vs. 42 instances, respectively). Birds that inherited natal territory did not have higher initial reproductive success than those that did not inherit. Comparing reproduction among birds who inherited, males and females did not differ either. Proportions of territory gained from the natal territory differed markedly between the sexes. Males gained a significantly higher percentage of their natal territory than females, and inherited territory made up a greater portion of their new territories. Males and females took different routes to inheritance: females showed higher plasticity in their acquisition strategy and more frequently paired with neighbouring, experienced widows on large territories, while males more commonly established new, relatively small territories with dispersing, novice females. Our study demonstrates the value in objectively quantifying field-gathered spatial data, as it revealed a previously unidentified trend of opportunistic female dispersals with beneficial fitness consequences.
Species loss alters the mesoscale structure of mutualistic networks.
Miguel MF, Jordano P, Burkle LA … +2 more , Emer C, Vázquez DP
J Anim Ecol · 2026 Jul · PMID 42175561 · Publisher ↗
Species extinctions represent one of the most alarming signs of the biodiversity crisis in the Anthropocene, with multiple impacts on ecosystems and human well-being. Local extinctions can trigger widespread changes in b...
Species extinctions represent one of the most alarming signs of the biodiversity crisis in the Anthropocene, with multiple impacts on ecosystems and human well-being. Local extinctions can trigger widespread changes in biotic communities by reshaping species composition and the structure of ecological interaction networks. However, we still know little about how species extinction alters the internal structure of ecological networks. We analysed how the loss of resource specialist animal species triggered by anthropogenic drivers affects frequencies of motifs-interaction patterns among small groups of species-and species positions within motifs in plant-pollinator and plant-seed disperser networks. Our results show that both motif frequencies and species positions changed after species loss in both systems, with variation primarily driven by a subset of large motifs involving five or six species, indicating that structural changes are concentrated in more complex interaction configurations. In plant-pollinator networks, variation in species positions was related to changes in species-level specialization, whereas in plant-seed disperser networks, motif frequencies varied with plant and animal species richness across sites. These findings indicate that species loss is accompanied by non-random structural reorganization at the mesoscale, and that these responses depend on ecological context and constraints on species interactions. By revealing patterns not captured by macroscale network descriptors, our study highlights the importance of considering intermediate levels of organization to understand how biodiversity loss reshapes ecological networks under ongoing environmental change.
Integrating infection intensity and aggregation into the dynamics of pathogens with within-host replication.
Sun R, Walsman JC, Wilber M … +1 more , Briggs CJ
J Anim Ecol · 2026 May · PMID 42174760 · Publisher ↗
Disease outcomes depend heavily on infection intensity which is often heterogeneous across and within host populations. Most individuals carry low pathogen loads and a few carry high loads, a pattern known as aggregation...
Disease outcomes depend heavily on infection intensity which is often heterogeneous across and within host populations. Most individuals carry low pathogen loads and a few carry high loads, a pattern known as aggregation. Although well characterized in macroparasite systems, aggregation and infection intensity are rarely incorporated into microparasite models. This raises key questions: Do similar mechanisms underlie aggregation in macro- and microparasite systems? Moreover, how do aggregation and load-dependent effects shape outcomes such as host suppression and virulence-transmission trade-offs? To address these questions, we developed a series of differential equation models that allow the pathogen load distribution across hosts to evolve dynamically, shaped by both within- and between-host processes. We applied this framework to the amphibian chytrid fungus system caused by Batrachochytrium dendrobatidis (Bd), a fungal pathogen threatening amphibian populations worldwide. Our results show that both stronger load-dependent mortality and faster within-host replication reduce aggregation. Aggregation, in turn, weakens host suppression and flattens virulence-transmission trade-off, shifting peak transmission to higher replication rates. Overall, our models show that similar mechanisms of infection intensity and aggregation influence host-pathogen dynamics in microparasites as in macroparasites. This work offers a framework for advancing theoretical and data-driven understanding of how within-host processes scale to population-level disease dynamics, advocating for a unified approach to disease modelling that bridges the macro- and microparasites.
Seasonal timing determines how warming affects mast-driven food webs.
Bogdziewicz M, Foest JJ
J Anim Ecol · 2026 Jul · PMID 42170763 · Full text
Research Highlight: Keesing, F., LaDeau, S., Canham, C., Oggenfuss, K., & Ostfeld, R. Climate warming, acorn masting and the dynamics of rodent populations: Comparing long-term studies. Journal of Animal Ecology. https:/...
Research Highlight: Keesing, F., LaDeau, S., Canham, C., Oggenfuss, K., & Ostfeld, R. Climate warming, acorn masting and the dynamics of rodent populations: Comparing long-term studies. Journal of Animal Ecology. https://doi.org/10.1111/1365-2656.70257. Mast seeding by forest trees drives consumer outbreaks and wider food-web dynamics, so climate-driven shifts in seed production are expected to cascade through ecosystems. Yet, long-term datasets that track both seed production and consumer responses remain rare. In a recent study, Keesing et al. combined two long-term datasets of acorn and rodent data, their 33-year-long study from New York and a 39-year Maine study by Dri et al., creating a rare opportunity to assess the generality of climate effects on mast-driven food webs. Despite warming and forest growth in both systems, acorn production, mouse abundance and mouse body mass increased only in Maine, whereas New York acorn production showed no directional increase, and mouse abundance remained tied to interannual variation in seed production. This contrast suggests that climate effects depend on the stage of reproduction during which warming occurs. These studies show that the acorn-mouse interaction is robust, but that the pathway from warming to seed production depends on seasonal climate change and species-specific reproductive mechanisms.
Biological invasions disrupt the relationship between size spectrum and trophic interactions in freshwater fish communities.
Marin V, Grenouillet G, Arranz I … +1 more , Cucherousset J
J Anim Ecol · 2026 May · PMID 42153539 · Publisher ↗
The size spectrum, which describes the relationship between abundance (or biomass) and body size, is an ataxic approach that can provide insights into energy fluxes across trophic levels. However, anthropogenic perturbat...
The size spectrum, which describes the relationship between abundance (or biomass) and body size, is an ataxic approach that can provide insights into energy fluxes across trophic levels. However, anthropogenic perturbations can alter the relationship between body size and trophic position, and therefore, the predator-prey mass ratio (PPMR). In this study, we used body size distribution and stable isotope analyses to investigate the relationship between size spectrum and the PPMR in lake fish communities across various eutrophication and invasion levels. Our results revealed that, although size spectrum and PPMR co-varied (i.e. resulting in flatter size spectrum when PPMR was low), this effect was modulated by the level of biological invasion in the community. This was likely caused by differences in trophic niche between native and non-native species: small non-native species exhibited higher trophic positions than small native species, while large non-native species can have lower trophic positions than their native counterparts. These findings suggest that the relationship between size structure and trophic interactions in lake fish communities may be blurred by anthropogenic perturbations, challenging core assumptions of size-based ecology in estimating energy fluxes within freshwater food webs.
Global meta-analysis reveals urban-associated behavioural differences among wild populations.
Burkhard TT, Dochtermann NA, Charmantier A
J Anim Ecol · 2026 May · PMID 42152172 · Publisher ↗
Urbanization causes fundamental changes to natural environments, causing rapid and substantial adaptive phenotypic change in wild populations. While many studies have investigated how urbanization may shape interspecific...
Urbanization causes fundamental changes to natural environments, causing rapid and substantial adaptive phenotypic change in wild populations. While many studies have investigated how urbanization may shape interspecific behavioural variation, for example, via urban environmental filtering, no study has yet quantitatively assessed broad, global patterns of urban-associated intraspecific behavioural variation. Here, we conducted a phylogenetic meta-analysis to assess urban-associated behavioural differences in wild populations of birds, mammals, amphibians, reptiles and insects. We focused on four commonly measured behaviours (boldness, aggressiveness, activity, exploration) and extracted paired urban-nonurban effect size estimates for behavioural means and variances (k = 279), repeatability (k = 13) and correlations (k = 14) from 81 unique studies. We found evidence that urban populations exhibited heightened average boldness, aggressiveness, exploration and activity compared to nonurban conspecifics, a result that was robust across geographic regions and ecological niches. However, avian species were strongly overrepresented in our meta-analysis (N = 49 studies) compared to other taxa (Mammalia, N = 20; Reptilia, N = 7; Insecta, N = 3; Amphibia, N = 2). Consequently, most behaviours in non-avian taxa were under-sampled, and effect sizes were generally not statistically significant: among non-avian species, only boldness differed significantly between urban and nonurban populations. This strong taxonomic bias potentially affects our other inferences as well. We did not find strong evidence linking urbanization to changes in behavioural variation, repeatability or correlations. Our results summarize data from the rapidly growing field of urban evolutionary ecology and demonstrate geographically widespread differences in behaviour between urban and nonurban populations. These patterns suggest that urban populations experience parallel directional selection or that urban invaders experience environmental filtering by common urban conditions that favour certain behavioural types. Taxonomic biases and methodological heterogeneity continue to limit inference in the field, constraining our ability to test preregistered hypotheses in this study. Broadening research to include understudied taxa such as invertebrates, herpetofauna and nocturnal species; incorporating common-garden approaches; and emphasizing clearer definitions for behaviour and urbanization will yield a more comprehensive understanding of how urbanization shapes animal behaviour and other ecologically meaningful phenotypes.
Predator-guild-specific parental responses mitigate higher predation risk on ground nests close to forest patches in a mosaic landscape.
Dillenseger G, Delautre J, Jayanth A … +3 more , Marchal Z, Veselý P, Kubelka V
J Anim Ecol · 2026 Jul · PMID 42144971 · Full text
The risk of nest predation differs across habitats and increases with proximity to habitat edges. In agricultural mosaic landscapes, the breeding success of ground-nesting birds can be negatively impacted by the presence...
The risk of nest predation differs across habitats and increases with proximity to habitat edges. In agricultural mosaic landscapes, the breeding success of ground-nesting birds can be negatively impacted by the presence of adjacent forest patches, which act as a source of predation. However, we still have limited knowledge on how birds nesting in such habitats cope with variable predation risk. In this study, we investigated predation rates of experimental ground nests and Northern Lapwing nests (Vanellus vanellus), in relation to the nearest patch. Furthermore, we tested the aggressive responses displayed by nesting pairs towards stuffed nest predators of different guilds at different distances from the forest. Predation rate on experimental nests increased with proximity and area of the closest forest patch. In contrast, predation rate on lapwing nests was not affected by the presence of forest, suggesting effective nest defence performed by parents to protect their clutch. Pairs displayed more aggressive behaviours against predators compared with a control wood log. Additionally, responses to specific predators varied with forest distance. Lapwings appeared more aggressive towards a bird when closer to forests, but were more aggressive towards a mammal further from forests. This study highlights the importance of fine-scale differences in anti-predatory behaviours to compensate for local variations in predation risk, in heterogeneous agricultural landscapes.
Riding out the storm: Behavioural responses of a large herbivore to high-Arctic winds.
van Beest FM, Hansen LH, Schmidt NM
J Anim Ecol · 2026 Jul · PMID 42144958 · Full text
Extreme weather poses serious challenges to wildlife, often forcing animals to alter their behaviour with potential population-level consequences. Following contemporary climate change, the number and intensity of Arctic...
Extreme weather poses serious challenges to wildlife, often forcing animals to alter their behaviour with potential population-level consequences. Following contemporary climate change, the number and intensity of Arctic storms are increasing, but the responses of Arctic species to wind speed and episodic storms are poorly documented. We aimed to quantify behavioural responses (i.e. changes in movement modes and habitat selection patterns) of muskoxen (Ovibos moschatus) to wind speed and to compare estimates from before, during and after storm to hurricane-level wind events (wind speeds ≥24.5 m/s on the Beaufort scale). Hourly positions of Global Positioning System (GPS)-collared adult muskoxen (N = 61) tracked in northeast Greenland between 2013 and 2024 were georeferenced with data on wind speed, precipitation class (with or without), elevation, terrain ruggedness and vegetation type. Statistical movement modes were estimated using unsupervised hidden Markov models, and habitat selection patterns were quantified using step selection functions for summer (June-August) and winter (September-May). Results showed that wind speed influenced the allocation of time between movement modes. Increasing wind speed reduced the amount of time spent in states characterized by intermediate step lengths and turning angles, suggesting a decrease in foraging activity. Changes in state-time budgets were most pronounced under wet conditions during summer, likely due to reduced fur insulation and increased thermoregulatory behaviour. Habitat selection patterns during calm conditions (e.g. selection for dense vegetation) were reinforced at increasing wind speeds. State-time budgets of muskoxen affected and unaffected by storms were comparable between days before and after episodic storm events. During storms, however, the allocation of time among movement modes shifted more towards states indicative of resting at the expense of states indicative of foraging and relocating, which differed from muskoxen unaffected by storms. Muskoxen adopt a simple energy conservation strategy of bedding down in dense vegetation habitat to buffer against negative impacts of high wind speed, without actively compensating for potential lost foraging opportunities during episodic storm events. However, as the Arctic climate continues to change, the energetic implications of increasing wind speed and frequency of storms on individual fitness and population performance represent a valuable area for future research.
A new approach to quantify isotopic (co)variation across levels of biological organization using double-hierarchical generalized linear models.
Garrido-de León F, Martin JGA, Costa-Pereira R … +2 more , Franco-Trecu V, Réale D
J Anim Ecol · 2026 May · PMID 42141815 · Publisher ↗
Double-hierarchical generalized linear models (DHGLMs) offer a powerful yet overlooked quantitative approach for analysing ecological data with hierarchical structures. DHGLMs account for unit-specific residual variances...
Double-hierarchical generalized linear models (DHGLMs) offer a powerful yet overlooked quantitative approach for analysing ecological data with hierarchical structures. DHGLMs account for unit-specific residual variances, allowing the estimation of variance components that expand our ability to quantify biodiversity patterns across levels of biological organization-from individuals to communities. A particularly promising application of these models lies in isotopic ecology, where stable isotopes of carbon (𝛿C) and nitrogen (𝛿N) are used to quantify continuous trophic (co)variation across individuals, populations and communities. Here, we show how DHGLMs can be a powerful tool for ecologists interested in trophic patterns and demonstrate the application of these models to isotopic data, showcasing study systems across three levels of biological organization. These examples illustrate how DHGLMs decompose (co)variance components within and across biological units of interest, uncover patterns of diet variation and ecological interactions. We also discuss the advantages, limitations and potential of DHGLMs for advancing research on different questions related to variation in diet and specialization at different biological levels.
Drought and growing season phenology over 35 years modulates species interactions among domestic and wild herbivores.
Ruprecht J, Forrester TD, Brown CL … +4 more , Mengak LF, Wisdom MJ, Clark DA, Levi T
J Anim Ecol · 2026 Jul · PMID 42130376 · Full text
Domestic animals represent the largest mammalian biomass on Earth, creating an urgent need to understand their effects on native species. Environmental change may further alter these interactions, particularly for large...
Domestic animals represent the largest mammalian biomass on Earth, creating an urgent need to understand their effects on native species. Environmental change may further alter these interactions, particularly for large herbivores that are highly sensitive to climate-driven resource availability. Interactions among assemblages of large herbivores include interference and exploitation competition, but the grazing optimization hypothesis paradigm suggests that interactions are often facilitative because defoliation from grazing stimulates compensatory regrowth of high-quality forage that benefits other species. We used 35 years of contemporaneous telemetry data on elk and domestic cattle to quantify spatial interactions within the context of climate-change-induced drought conditions. We fit step-selection functions to assess the immediate response of elk to spatiotemporal cattle distribution and tested whether drought and phenological advancement of the growing season-mediated interactions. We also modelled elk selection for pastures that were ungrazed, currently grazed or previously grazed by cattle to assess competition and facilitation. Our results refute the grazing optimization hypothesis and suggest elk are not attracted to areas previously grazed by cattle. Instead, elk avoided cattle throughout the entire growing season and at multiple scales. Elk were 2.9 times more likely to make movements to locations without cattle versus locations with 1 cow-calf pair/hectare, 23% less likely to use a pasture with cattle present, and 27% less likely to use one grazed by cattle earlier in the season, compared to an ungrazed pasture. After controlling for current season grazing status, elk were 30% less likely to use a pasture if it was grazed the previous year. Resource availability, influenced by growing season phenology and drought, mediated the magnitude of avoidance of cattle by elk. In the periods of most severe drought, elk reduced their avoidance of cattle ostensibly to seek out the remaining palatable forage regardless of cattle presence. Increased overlap between domestic and wild ungulates should be anticipated as climate change continues to increase the intensity and frequency of drought, which may result in decreased weight gain or fitness consequences to both species, increased potential for disease transmission, and more encounters between predators and domestic livestock.
Flexible parental care in a songbird correlates with sex-specific responses to seasonal phenology, mating opportunity and reproductive success.
Zheng J, Jiang W, Wang H … +3 more , Zhang Z, Chen D, Komdeur J
J Anim Ecol · 2026 Jul · PMID 42130370 · Full text
Species with diverse parental care systems exhibit flexibility in response to environmental changes. Such changes can influence parental care decisions by altering the trade-offs between current and future reproduction....
Species with diverse parental care systems exhibit flexibility in response to environmental changes. Such changes can influence parental care decisions by altering the trade-offs between current and future reproduction. While previous studies have revealed correlations between specific social and ecological factors and parental care systems, the joint effects of multiple factors could be complex and may result in different outcomes within and across populations and between sexes. In this study, we observed parental care systems and their seasonal variations across three geographic populations in a polygamous species, the Chinese penduline tits (Remiz consobrinus), by monitoring breeding events over 8 years. In this species, biparental care, female-only care, male-only care and biparental desertion coexist in one population. To investigate whether and how sex-specific parental care patterns correlate with local conditions, we compared breeding phenology, season length, mating opportunity and reproductive success and their associations with the frequency of parental care patterns observed within and across the populations. We found striking population differences in the parental care system: biparental care predominated in one population, whereas female-only care was more common in the other two. These divergent parental care systems were shaped by sex-specific responses to the interacting local conditions. In all three populations, females synchronised egg-laying and offered males a short but highly successful re-mating window. This resulted in rapidly decreased male mating opportunities due to male collective clutch desertion. Males were more likely to care when re-mating opportunities were low. In contrast, females consistently provided care, regardless of variations in female mating opportunities. Additionally, males deserted clutches more in populations where desertion resulted in no fitness cost to the current broods. We found that desertion costs on brood fitness matter more than achieving a high reproductive reward in driving uniparental care, contrary to the theory that uniparental care only occurs when single parents can raise young efficiently. Our study demonstrates that parental care system variance across populations could result from the combined influences of social and ecological conditions, and their interactions. We highlight the consistency of sex-specific responses to local conditions in parental care.
Does energy minimisation constrain behavioural plasticity? Long-term activity budgets of a model folivore-frugivore.
Dias PAD, Rangel Negrín A
J Anim Ecol · 2026 May · PMID 42130313 · Publisher ↗
Optimal foraging theory predicts that time-minimising foragers should reduce activity when resources are abundant, yet empirical tests examining how dietary generalists modulate activity budgets in response to multiple e...
Optimal foraging theory predicts that time-minimising foragers should reduce activity when resources are abundant, yet empirical tests examining how dietary generalists modulate activity budgets in response to multiple environmental and intrinsic factors remain scarce. We analysed 6693 focal samples collected over 10 years from 21 mantled howler monkeys (Alouatta palliata) inhabiting a tropical rainforest in Los Tuxtlas, Mexico, to test predictions derived from energy minimisation theory. Using beta regression models with cyclical time controls, we examined how young leaf availability, fruit availability, ambient temperature, relative humidity, daily rainfall, age and reproductive state influenced the proportion of time allocated to resting, feeding, locomotion and social behaviour. Young leaf availability exerted effects nearly 40 times stronger than fruit availability on activity budgets, with increased leaf availability associated with reduced feeding and increased resting. Temperature positively predicted resting time and negatively predicted feeding time, with post hoc breakpoint analysis identifying a threshold at 31.6°C above which resting increased sharply, consistent with a transition from behaviourally flexible to thermally enforced inactivity. Relative humidity did not significantly predict any activity, suggesting temperature alone drove the thermoregulatory constraint on behaviour under the conditions observed. Lactating females rested more than cycling females but did not increase feeding time, suggesting energy conservation rather than intake maximisation during the most energetically demanding reproductive phase. Age had no detectable effect on any activity category across the 3-31-year age range, indicating that time allocation strategies are established early and maintained throughout adulthood. Variance attributable to year exceeded that attributable to individual identity or social group, highlighting the importance of interannual environmental fluctuation in shaping behavioural flexibility. Contrary to predictions that resting should remain invariant as an energetic baseline, resting was the most responsive activity to environmental variation, functioning as a behavioural buffer that absorbs fluctuations in resource availability and thermal conditions, although this flexibility is constrained above a critical temperature threshold with implications for population resilience under projected climate warming. These findings support time-minimisation strategies in folivore-frugivores and provide a framework for understanding behavioural responses to environmental change in energy-limited tropical primates.
Ocean acidification, more than warming or heatwaves, constrains shoaling behaviour in a range-extending fish through habitat simplification.
Mitchell A, Connell SD, Hart ME … +7 more , Harvey BP, Agostini S, Spatafora D, Izumiyama M, Booth DJ, Ravasi T, Nagelkerken I
J Anim Ecol · 2026 May · PMID 42116573 · Publisher ↗
Social context is a critical yet underexplored determinant of behavioural resilience to climate change. Group living can buffer individuals against environmental stress through enhanced vigilance, reduced predation risk...
Social context is a critical yet underexplored determinant of behavioural resilience to climate change. Group living can buffer individuals against environmental stress through enhanced vigilance, reduced predation risk and improved foraging efficiency. However, whether these behavioural expressions persist under chronic (warming, acidification) and acute (marine heatwaves) climate stressors remains unclear. Using natural climate analogues spanning present-day, ocean warming and combined warming-acidification reefs, we quantified how shoal size influences behavioural expression in a range-extending reef fish (Pomacentrus coelestis). Across all climate conditions, fish in larger shoals consistently exhibited higher foraging and activity levels and reduced risk-avoidance behaviours, whereas direct effects of warming, acidification and heatwaves on behaviour were negligible. In contrast, ocean acidification most likely constrained collective behaviour indirectly by simplifying benthic habitats, where fish densities were 84% lower than at the warming reef, resulting in shoals that were up to 79% smaller than the Warming and Control reefs. Combined, our data suggest that shoal size mediates behavioural expression between foraging and predator avoidance and that acidification-driven habitat simplification can alter behavioural expression indirectly by reducing fish densities and the formation of large shoals. We conclude that climate change can indirectly modify behavioural expression in shoal-forming fishes through habitat-driven erosion of social structure.
Digging into dirt: Rewilding with threatened mammals shapes soil-emerging insect assemblages.
Johanson LG, Contos P, Rader R … +1 more , Gibb H
J Anim Ecol · 2026 Jul · PMID 42104670 · Full text
Digging mammals function as ecosystem engineers by altering soil structure, influencing nutrient cycling and shaping vegetation communities. The widespread decline of these taxa globally, driven by habitat loss and intro...
Digging mammals function as ecosystem engineers by altering soil structure, influencing nutrient cycling and shaping vegetation communities. The widespread decline of these taxa globally, driven by habitat loss and introduced predators, has triggered cascading ecological effects, yet the consequences for soil-dwelling insect communities remain poorly understood. Insects, many of which have subterranean larval stages, provide essential functions such as pollination, decomposition and nutrient cycling, making them ideal indicators for evaluating the restructuring of ecological communities following mammal reintroductions. Here, we used data from a long-term experimental mammal exclusion study within a predator-free sanctuary (Scotia Wildlife Sanctuary) in south-eastern Australia to test how the reintroduction of digging mammals affects the structure and composition of insect communities emerging from soil. We sampled insects using emergence traps across replicated plots of mammal reintroduction, exclusion, and procedural control in 2010 and in 2018, 8 years after fence installation. While variation in digging activity (indexed by pit density) did not significantly affect richness or biomass of soil-emerging insect taxa, areas with digging showed reduced insect abundance. Hierarchical modelling of taxa communities revealed that parasitoid wasps (Hymenoptera) and predatory robber flies (Diptera: Asilidae) were strongly associated with plots without digging activity, likely reflecting sensitivity to direct predation or nest disturbance. No herbivorous beetle taxa showed a statistically supported association with treatment, indicating that negative associations with digging activity were restricted to specific parasitoids and predatory groups, rather than representing a consistent trophic-wide response. Our findings therefore indicate that the reintroduction of ecosystem engineers alters insect assemblages, potentially cascading through to multitrophic interactions and ecosystem functioning. This is important because it (1) suggests there may have been profound effects of the widespread loss of ecosystem engineers on ecosystems across the Australian continent; and (2) highlights that whole-of-ecosystem knowledge is critical to getting rewilding right. We emphasise the importance of thorough, long-term ecological monitoring of invertebrate assemblages to inform mammal reintroduction and restoration efforts, ensuring they align with broader ecosystem management objectives.
Biogeographic shifts in reef fish size structure along the Southeastern Pacific occur independently of sea surface temperature and chlorophyll-a.
Gartenstein S, Garcés-Vargas J, Villalobos VI … +5 more , Fica-Rojas E, Godoy N, Torres Cañete F, Pérez-Matus A, Valdivia N
J Anim Ecol · 2026 May · PMID 42083304 · Publisher ↗
Body size is a key functional trait linking individual physiology to ecological interactions and community structure. Size spectra provide a trait-based framework to quantify how community size structure responds to envi...
Body size is a key functional trait linking individual physiology to ecological interactions and community structure. Size spectra provide a trait-based framework to quantify how community size structure responds to environmental gradients, yet their large-scale drivers remain poorly understood. We tested whether temperature and productivity differentially shape reef fish size structure, examining how sea surface temperature (SST) and chlorophyll-a (Chl-a) influence size spectra and total biomass across a broad latitudinal gradient. Reef fish communities were consistently dominated by small-bodied individuals, but cooler continental systems supported a higher proportion of medium to large fishes. Species richness declined with latitude, indicating strong biogeographic filtering across regions. Size-spectrum exponents significantly differed among regions, reflecting shifts in the relative contribution of small versus large individuals. In contrast, variations in SST and Chl-a had no detectable effect on total biomass. Synthesis. The broad latitudinal patterns in these fish assemblages are governed primarily by shifts in community composition and size spectra, with SST exerting reduced effects, whereas total biomass shows limited variation across environmental gradients. This stresses the importance of conserving size structure-especially larger individuals-alongside biomass and supports management approaches that incorporate spatial ecoregional heterogeneity to safeguard size spectra at large geographic scales.
Plasticity in parental care: Interspecific competitor cues shape biparental cooperation in a burying beetle.
Patmore C, Smiseth PT
J Anim Ecol · 2026 May · PMID 42083286 · Publisher ↗
Interspecific competition is an important evolutionary driver of many species' life histories and behaviours, arising wherever species come into conflict over limited resources. However, how such competition shapes the p...
Interspecific competition is an important evolutionary driver of many species' life histories and behaviours, arising wherever species come into conflict over limited resources. However, how such competition shapes the plasticity of social behaviours within a species, such as biparental care, remains less clear. The burying beetle Nicrophorus vespilloides is an insect that exhibits biparental care, relying on small vertebrate carcasses to breed on. Such carcasses are highly valuable but relatively rare in nature, and so are competitively sought out by many other species, including the bluebottle fly, Calliphora vomitoria. Despite the close association and frequent rivalry between the two species, how their interactions shape biparental care decisions in these beetles has received little attention. We investigated how perceived risk of interspecific competition affected breeding success and duration of male and female care by staging encounters between breeding pairs of beetles and fly intruders. We presented breeding pairs with dead flies, at varying times and densities, to assess changes in duration of care and fitness outcomes. We used dead flies to ensure the beetles' response was driven solely by cues associated with flies, rather than direct interaction or resource depletion. We found that the duration of both male and female care was plastic in response to the presence of competitors, as both increased their duration of care. However, these encounters also increased breeding failures, with the strongest effects occurring when encounters took place early in the breeding attempt. Our results demonstrate plasticity in parents' behaviour in response to a perceived competitive threat, but this plastic response was associated with increased breeding failures, suggesting a trade-off between dealing with competitors and completing other parental tasks.
Contrasting properties of predation and scavenging networks governed by megaherbivores in an African savannah.
Batista-Nunes SA, Sebastián-González E, Broekhuis F … +3 more , van Langevelde F, Mogensen N, Moleón M
J Anim Ecol · 2026 Apr · PMID 42052927 · Publisher ↗
Predation and scavenging are two faces of carnivory that operate under distinct ecological rules, yet food web research often overlooks this distinction by ignoring scavenging or conflating it with predation. Using an 8-...
Predation and scavenging are two faces of carnivory that operate under distinct ecological rules, yet food web research often overlooks this distinction by ignoring scavenging or conflating it with predation. Using an 8-year dataset of mammalian carnivore feeding events from the Maasai Mara (Kenya), we explicitly separated predation and scavenging to compare their network structure. The study system includes a diverse carnivore guild and a broad herbivore prey size spectrum, including megaherbivores (>1 ton). We assessed two network properties (nestedness and modularity), identified species contributions to network structure and examined the relationships between these species-level contributions and body mass, between the number of interaction events per link and prey/carcass body mass, and between consumer and resource body mass. Despite largely involving the same species, the two networks differed markedly: both were nested, but only the predation network was modular, with modules aligned with prey size classes. As expected, body-size asymmetries structured the two networks in contrasting ways: predation was mostly limited to prey of similar or smaller size than the predator, with a sharp decline above the megaherbivore threshold, whereas larger carcasses, especially those of megaherbivores, attracted more scavenger species. The most influential species across metrics and network types was a herbivore, particularly the wildebeest, except for the lion in weighted nestedness within the predation network. These species-level contributions to network structure were unrelated to body mass. Relationships between consumption degree and prey/carcass body mass differed between networks, and predator-prey body mass correlated positively, unlike scavenger-carcass body mass. These asymmetries reveal opposing size-based constraints, with predation being more tightly constrained by body size than scavenging. Although similar patterns have been suggested previously, no study has directly compared both networks within the same system. Overall, our results show that predation and scavenging are complementary, not functionally redundant, components of carnivory food webs. We also propose a scalable framework for cross-ecosystem comparisons of species-level differences in network structure. Distinguishing scavenging from predation is essential to fully reveal the true architecture of food webs and the mechanisms governing energy flow through ecosystems.
Invasive goldfish trigger a regime shift in experimental lake ecosystems of varying trophic state.
Hintz WD, Barrett H, Relyea RA
J Anim Ecol · 2026 Apr · PMID 42046097 · Publisher ↗
The ongoing pressure of biological invasions caused by the pet trade continues to restructure the earth's ecosystems. The release of pets and ornamentals has altered species interactions, ecosystem functions, spread dise...
The ongoing pressure of biological invasions caused by the pet trade continues to restructure the earth's ecosystems. The release of pets and ornamentals has altered species interactions, ecosystem functions, spread disease and rewired food webs. We assessed the effects of a high-risk, yet understudied invasive species-that is, goldfish, Carassius auratus-on experimental freshwater ecosystems by integrating additive and substitutive experimental designs across two trophic states (i.e. oligotrophic vs. eutrophic). We hypothesized that goldfish would trigger a regime shift characteristic of more algae, reduced water quality and negative impacts on native species across multiple trophic levels. Under eutrophic conditions, goldfish induced a rapid shift in mesocosm state characterized by increased suspended solids and reduced water clarity; however, increases in phytoplankton and reductions in filamentous algae were largely driven by total fish density (native or invasive), consistent with strong niche overlap between the two species. Through consumption and habitat loss, goldfish caused reductions in snails, amphipods and zooplankton. Goldfish also reduced native fish condition, likely through exploitative competition. Our results indicate that goldfish are undesirable for both oligotrophic and eutrophic lakes, although some impacts will depend on trophic state. These results suggest that natural resource managers worldwide should consider management action to reduce or prevent goldfish invasions. Despite many viewing goldfish as signs of prosperity, luck and wealth, it is critically important to inform the public that their pets can grow into sizable pests that will harm freshwater ecosystems.
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